This invention relates to plate-type heat exchangers. More particularly, this invention relates to plate-type heat exchangers useful for exchanging heat between two or more fluids of differing heat content.
Heat exchangers provide a means for transferring thermal energy from one fluid stream to another while permitting no mixing of the streams to occur. It is known that heat exchange between a cold stream entering a process and a hot stream produced in or leaving the process reduces the total energy requirement of that process by recycling the heat energy provided by the hot stream. As a result, heat exchangers are commonly used in thermoelectric devices such as furnaces, incinerators and the like to increase the energy efficiency of such devices through the use of recycled heat energy.
Various types of heat exchangers exist, such as, for example, plate-type heat exchangers, fin and tube-type heat exchangers, and shell and tube-type heat exchangers. Plate-type heat exchangers are generally less expensive and easier to make than the other types of heat exchangers. As a result, plate-type heat exchangers tend to be more widely used in industrial applications requiring high performance and efficiency with relatively low cost, small volume, and light weight. Such applications include, for example, vehicle gas turbines.
Although plate-type heat exchangers are generally less complicated and more easily made than the fin- and tube-types of heat exchangers, many plate-type heat exchangers are still undesirably bulky and expensive to make. For example, the plates in many conventional plate-type heat exchangers are made of thick metal. Such thick metal plates make these plate-type heat exchangers bulky and, therefore, more expensive to make, inspect, clean, re-use or replace. In addition, plate-type heat exchangers generally contain at least two heat exchange plates and frequently more.
It would be desirable, therefore, to provide plate-type heat exchangers which are less bulky. Less bulky plate-type heat exchangers can be produced more economically and more efficiently on demand with a variety of different interchangeable structures to satisfy a wide variety of needs.
Plate-type heat exchangers are disclosed, for example, in U.S. Pat. Nos. 4,308,915; 5,025,856; 5,271,459; 4,572,766; 4,310,960; 3,255,817; 4,407,357; 4,335,782; and 4,073,340.
U.S. Pat. No. 4,308,915 to Sanders et al. discloses a thin sheet heat exchanger for transferring heat between two gases, wherein the sheets may have formed therein a crossflow pattern, a combination of a crossflow and a counterflow pattern or any other combination of channel patterns.
U.S. Pat. No. 5,025,856 to VanDyke et al. teaches a crossflow, plate-type heat exchanger for transferring heat between first and second fluids, wherein the heat exchanger is composed of a plurality of heat conductive plates having channels formed therein by micromachining methods such as etching.
U.S. Pat. No. 5,271,459 to Daschmann discloses a plate-type heat exchanger for exchanging heat between two fluids, wherein the heat exchanger is composed of a plurality of stacks of form-stamped plates combined to form pairs and the pairs assembled atop one another to form one stack. First flow channels for a first fluid are formed between the plates of one pair and second flow channels for a second fluid are formed between adjacent ones of the pairs, the stacks being arranged directly adjacent to one another to form a stack assembly.
U.S. Pat. No. 4,407,357 to Hultgren discloses a thin, metal heat exchanger having countercurrent flow of media on opposite sides of spaced walls.
U.S. Pat. No. 4,572,766 to Dimitriou discloses a plate evaporator or condenser having a plurality of plates forming a plate stack and defining alternating chambers in separate plates for a first fluid to be evaporated and a second fluid to be condensed.
U.S. Pat. Nos. 4,310,960; 4,073,340; and 4,335,782, all to Parker, disclose plate-type heat exchangers composed of a stack of relatively thin material, spaced heat transfer plates. The plates define sets of multiple counterflow fluid passages for two separate fluid media alternating with each other. Each plate contains a flow path for one of the two fluid media. The plates are arranged so that one fluid stream flows in one direction between adjacent streams of the other fluid which flows in an opposite direction.
U.S. Pat. No. 4,823,867 to Pollard et al. discloses a heat exchanger composed of a core element, wherein the core element contains a plurality of substantially parallel plates in stacked relationship to define a multiplicity of flow passages for a working fluid alternating with a plurality of flow passages for a process fluid, the working fluid flow passages being substantially parallel to the process fluid flow passages.
U.S. Pat. No. 3,255,817 to Davids et al. teaches a plate-type heat exchanger composed of horizontally stacked or nested heat exchange plates providing three fluid flow heat exchange paths in the heat exchanger.
Energy efficient heat pumps composed of a condenser, an evaporator, and a compressor made by photoetching tiny grooves and channels which are "about two human hairs deep" into a "piece of metal about the size of a dime" are described in Business Week, p. 129, May 30, 1994.
The heat exchangers disclosed in the references cited above require at least two heat exchange plates. None contain only one heat exchange plate. It would be desirable to provide a heat exchanger which can provide heat exchange using only one heat exchange plate. It would be further desirable to provide a heat exchanger which can provide heat exchange on a single surface of a single heat exchange plate.
Furthermore, while some of the heat exchangers disclosed in the references cited hereinabove provide high surface-to-volume ratios and some of the heat exchangers provide countercurrent heat exchange between two heat exchange fluids, none appear to provide both high surface-to-volume ratios and countercurrent heat exchange. It would be desirable to provide a heat exchanger which can provide both a high surface-to-volume ratio and countercurrent heat exchange.
A further drawback of conventional heat exchangers is their failure to provide three-dimensional heat exchange. It would be desirable to provide a heat exchanger which can provide three-dimensional heat exchange.
Accordingly, a primary object of this invention is to provide a heat exchanger capable of providing heat exchange using a single heat exchange plate.
A further object of this invention is to provide a heat exchanger capable of providing heat exchange using only a single surface of a single heat exchange plate.
A further object of this invention is to provide a heat exchanger which is less bulky and less expensive to make, inspect, clean, re-use or replace.
Another object of this invention is to provide a heat exchanger capable of providing both a high surface-to-volume ratio and countercurrent heat exchange.
A further object of this invention is to provide a heat exchanger capable of providing three-dimensional heat exchange.
An additional object of this invention is to provide a method of exchanging heat between two or more fluids of differing heat content, using a heat exchanger having the properties described in the foregoing objects.
These and other objects which are achieved according to the present invention can be discerned from the following description.